Geomorphic Evidence of Active Faulting
(Click to enlarge)
The Earth's surface is transformed by movement along active faults, producing features that help us determine the location of the fault and are diagnostic of the fault's level of activity. Examples are provided in the block diagram above. These various features are shown on the map using the codes and abbreviations listed below.
G - GEOMORPHIC FEATURES
Codes indicating strength of the evidence
G1 - strongly pronounced feature
G2 - distinct feature
G3 - weakly pronounced feature
? - additional uncertainty in tectonic
origin
Codes:
af - alignment
of multiple features as listed
as - arcuate scarp
bt - downthrown surface tilts back toward
fault
df - depression formed by some aspect of fault deformation, undifferentiated
dr - sag, depression formed in right stepover
of fault trace
gi - linear break (or gradual inflection) in
slope
hb - linear hillside bench
hv - linear hillside
valley
ls - fault scarp height enlarged by
landsliding
lv - linear valley or trough
mp - Youngest traces disturbed by human activities. Mapped trace bisects disturbed zone. Location uncertainty (dash gap in linework) equals half width of disturbed zone.
n - notch
pr - pressure ridge in left stepover
rr - right-laterally offset ridge
line
rs - right-laterally offset stream or gully
sb - broad linear scarp (implies multiple traces)
sc - scissor point, sense of vertical
separation reverses
se - subsoil exposed
sl - linear scarp, undifferentiated
sn - narrow linear scarp (implies dominant trace)
sp - spring
ss - swale in saddle
vl - line of vegetation
See Block Diagram of
Geomorphic Features
used as Evidence for Active Faulting
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